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(Np Model.) 3 Sheets-Sheet, 1; J. J. GRANT. MACHINE FOR GRINDING BALLS.

No. 535,794. PatentedMar. 12, 1895.

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MACHINE FOR GRINDING BALLS. No. 535,794. Patented Mar. 12, 1895.

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J. J. GRANT.

MACHINE FOR GRINDING BALLS.

No. 535,794. Patented Mar. 12, 1895. h 3% A 7701mm.

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Uwrren STATES P TENT OFFICE.

JOHN J. GRANT, OF FITCHBURG, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO WILLIAM W. SWAN, ALFRED BOWDITCH, AND WAL- DRON BATES, TRUSTEES.

MACHINE FOR GRINDING BALLS.

SPECIFICATION forming part of Letters Patent No. 535,794, dated March 12, 1895.

Application filed August 1, 1890. steam). 360,656. (NomodelJ To all whom it may concern.-

Be it known that I, JOHN J. GRANT, of Fitchburg, county of Worcester, State of Massachusetts, have invented an Improvement in Methods of and Machines for Grinding Balls, of which the following description, in connection with the accompanying drawings, isa specification, like letters and numerals on the drawings representing like parts.

The object of this invention is to grind balls such as are used for bearings so as to bring them as nearly as possible to'accu-rate spherical shape and uniform size. The balls which are especially intended for use in anti-friction hearings, and are commonly required to be of extreme accuracy in shape and uniformity in size, are first made approximately to the shape and size required, by forging or otherwise, and the present invention involves a new method of grinding the surfaces of the forged balls and new machinery therefor. The grinding is effected by novel means for holding and presenting a series of balls to the action of a rotating grinding wheel in such manner that each ball is brought repeatedly to the action of the grinding wheel and has different portions of its surface presented to the grinding wheel at each action of the latter in such manner that in the continued operation all parts of the surface of each ball will be acted upon, so that each ball is finally brought to substantially uniform diameter in all directions or in other words to true spherical shape, while those balls which are originally slightly larger than the others of the series are reduced to the same size as the rest. In order to accomplish these results, the balls must be kept in constant rotation around constantly changing axes during the grinding operation, and must be 'held with sufiicient firmness to present considerable resistance to the action of the grinding wheels so that the latter may act effectively to cut the portion of the surface at each time presented to them. These conditions are secured by the machine forming the subject of this invention which comprises a stationary circular raceway having two surfaces at an inclination to one another against which the peripheries of the balls rest and a rotating platen or head piece provided with a surface that engages the balls while supported on the raceway, the balls thus being engaged at three points by the surfaces of the raceway and rotating platen or head, the rotary movement of which latter causes the series of balls to roll along in the raceway. If the balls are originally untrue or egg-shaped, the surfaces that engage them tend to cause them to rotate around their largest diameters as an axis, and thus to present the more projecting parts to the grinding wheels. A portion of the periphery of each ball projects out from between the raceway and platen and is carried across the periphery of the grinding wheels, as the ball passes the grinding wheels in its rolling motion in the raceway, and the position of the ball engaging surfaces is such that as a result of the forces acting upon them, the balls are constantly shifting their axis of rotation sothat different portions of their peripheries are presented to the grinding wheels in the successive passages of the balls by the same.

The surface of the grinding wheels in engaging with that of the balls tends to rotate the latter about an axis parallel with that of the grinding wheel and the surfaces of the raceway and rotating platen clamp the balls so as to resist to a greater or less extent their tendency to rotate and thus enable the grinding wheel to have an efficient cutting action, and as the entire series of balls are held or clampedbetween the same surfaces it is evident that any ball which is of smaller size than the rest will be less firmly held and will also project a less distance from the raceway toward the grinding wheel and consequently will not be reduced by the grinding action, until the larger balls have been ground to practically the same size, so that inthe continued action of the machine the entire series of balls in the raceway will be brought to the same diameter or to uniformity in size while each ball is brought to true spherical shape, and the grinding operation is performed very rapidly and at comparatively small cost.

Figure 1 is a front elevation of a machine for grinding balls embodying this invention; Fig. 2, an end elevation thereof, and Fig. 3 an enlarged View showing parts that contain the ball supporting raceway partly in elevation and partly in vertical section.

The balls (1 to be ground are supported on a raceway formed in a ring I), having ball supporting surfaces inclined to one another as best shown in Fig. 3, the said ring being connected with a bed piece or plate chaving a central hub or shank 0 (see Fig. 1) contained within a suitable bearing sleeve d, supported in a projecting socket piece e forming part of the main frame work or cas'tingf of the machine. The base plate 0 of the raceway is capable of rotating in the bearing sleeve 61 from time to time, for the purpose of adjustment but does not rotate in the operation of the machine being restrained from roration by a fastening device or lock 0 see Fig. 2', shown as a sliding bolt the end of which normally engages with one of a series of notches 6 around the periphery of the said base plate 0.

The grinding wheels g, g shown in thisinstance as two in number although if desired a greater-number may be used, are supported in bearings on carriages g which are adjustable toward and from the raceway on guides g on a platform 9 supported on the main frame workf said platform being shown as Vertically adjustable on a guide wayf on said frame work by means of an adjusting screw 9 "When the platform g is set at the proper height to bring the grinding wheels g, 9 in the proper position with relation to the balls supported on the raceway it is fastened by bolts 9 as shown in Fig. 1.

The grinding wheels 9 are rotated rapidly in any suitable manner as by belts passed over pulleys 9 see Fig. 2, connected with the said wheels, and the balls aare supported on the raceway as shown in Figs. 1, and 3, with their peripheries projecting out beyond the edge of the raceway far enough to be acted upon by the surface of the grinding wheels.

In order to insure the proper grinding action on all of the balls in the series supported on the raceway it is necessary that the said balls should be caused to travel or roll around the raceway each one in turn passing the surface of the grinding wheels and being acted upon thereby, and it is also necessary that the balls should be held with some firmness in the raceway as they pass by the grinding surfaces so that the latter will have an efficient cutting action on the surface of the balls, and it is also necessary that different portions of the surface of the balls should be presented to the grinding wheels from time to time, as the balls pass so that ultimately the entire surface of each ball will have been acted upon by the grinding wheels. These effects are produced by the rotating platen iwhich is supported on a shaft 2' concentric with the axis of the raceway and is provided with a hearing ring 2' which engages with the balls supported on the raceway as best shown in Fig. 3, so that when the platen z' is caused to rotate the ring 2' therein rolls upon the series of balls at the same time rolling the balls themselves around in the raceway b.

The raceway is formed at the upper outer edge of a cylindrical ring and is almost directly on a level with the axis of the grinding wheels, the plane of rotation of which is parallel with the axis of the raceway. One surface 2 of the raceway is nearly horizontal or at right angles to the line of movement of the grinding surfaces at a point where it acts upon the balls but said surface2 is slightlyinclined inward so that the balls will not easily roll off when applied to the raceway when the platen is raised. The other surface 3 of the raceway is about. at right angles to the surface 2, that supports the balls, and said surface 3 acts as an abutment to hold the balls forward to the action of the grinder which can thus reduce the balls only to a diameter equal to the distance between the said surface 3, and the nearest point on the surface of the grinder. The surface of the platen ring 2' is inclined so that when resting on the balls it tends to wedge them back against the surface 3 of the raceway; and the surface of the ring i and the supporting surface 2 of the raceway converge toward the grinder so as to confine the balls in the track or raceway, holding them back against the surface 3 of the raceway so that only such portions of the balls as are of longer diameter than the distance from the surface 3 to the surface of the grinder will be cut. Each ball is thus engaged at three points, one by the ring i which rolls upon the balls, and the other two by the surfaces of the raceway on which the balls roll, such surfaces having the proper relations to one another and to the grinding wheels to confine the balls as shown in Fig. 3, while permitting a portion of the periphery to extend outside of the outer surface of the raceway ring I) and the ball actuating ring r so as to be acted upon by the surface of the grinding wheels g, 9 as the balls roll past them on the raceway.

The parts that engage the balls hold them with sufficient firmness to cause the surface of the grinding wheels to act effectively upon the projecting portions of the balls presented to the said grinding wheels, which latter will tend to turn the balls more or less from the position they would naturally occupy if rolling freely and thus cause different parts of the surface of the balls to be presented to the grinders as the balls roll by, and the supporting surfaces of the raceway are set at such an inclination that the balls naturally roll on an axis or diameter inclined to that which is presented to the grinding wheels the result of these actions being that different portions of the balls are presented to the surface of the grinding wheels in the different passages of the balls by the grinding wheels, so that finally the entire surface of each ball has been acted upon by the grinders and the ball is brought to uniform diameter in all directions or to true spherical shape.

The shaft 2' by which the platen i is rerated for the purpose of rolling the balls past the grinders as just described, has its hearing in a sleeve or bushing is capable of moving longitudinally in a lining m contained in a socket n formed in the overhanging part of the framework f the said lining m being preferably of comparatively soft metal which may be run in between the bushing and the socket matter the shaft has been properly centered with relation to the base piece and raceway on which the balls roll.

The shaft 2' has a splined connection as shown at 01 Fig. 1, with a worm gear t mesh ing with a worm i operated by a pulley i see Fig. 2, driven by a belt or in any other suitable manner, by which the said shaft t and ring 2' resting on the balls are rotated.

In order to provide for the introduction of balls into the raceway it is necessary that the ring 2' should be raised and for this purpose the bearing sleeve his engaged at its ends with the shaft "6 as shown in Fig. l, and said sleeve is capable of longitudinal movement in thelining refer the purpose of raising and lowering the shaft '5 and ring 2' For convenience in operating the machine the said sleeve is is connected with a strap 0, see Fig. 2, passing over suitable guide pulleys 0 and connected with atreadle 19 which is depressed by the operator when it is desired to raise the ring i for the purpose of removing the balls.

that have been ground and introducing the balls that are to be ground.

The balls may be most conveniently removed from and inserted into the raceway b by rotating the same after the platen has been raised and for this purpose the locking bolt 0 for the raceway and base plate, is withdrawn fromthe notch of said plate, in which it may be resting, the said bolt being for convenience connected by a strap 0", see Fig. 2, with the same treadle 19 that operates to raise and lower the platen and the said strap 4" being made somewhat slacker than the strap 0 as shown,so that the platen will'be raised by the action of the strap 0 before the bolt 0 will be withdrawn by the strap 0". After the raceway is filled and while the series of balls supplied thereto at any one time is being ground the grinding wheels g, 9 remain opposite the same points on the raceway and the tendency to wear the surface of the raceway is greater at this point than around those portions where the balls are not exposed to the grinding action and in order to equalize the wear from time to time the raceway base is provided with a number or series of the locking notches 0 so that it may be locked in different positions with relation to the grinders from time to time and thus cause the wear to be distributed throughout the raceway.

The bearing surfaces of the raceway and of the ring i that cause the balls to roll about the raceway have to be accurately made in order to insure the proper grinding action on the balls and these are the surfaces which are mainly exposed to wear in the operation of themachine and thus require to be dressed or renewed from time to time. In order to facilitate this operation the raceway ring I) and the bearing ring '6 are each removable from their supports the ring 1) being shown as mounted on an annulus 19 see Fig. 3, connected with its bearing base piece 0 by screws 12 so that by loosening the said screws the said ring may be removed and the supporting surfaces ground to proper shape to act prop: erly on the balls. The ring 1' is also provided with an annulus t engaged by a notched bolt 15 operated by a screw 25 so that the said ring and annulus may be readily removed when it is desired to grind the ball engaging surface of the ring.

In the operation of the machine the power is applied to the pulley t which causes rotation of the platen i and ring 71 and the grinding wheels g, g are also rapidly rotated by power. Theplateniisraisedbydepressingthe treadle p, and at the same time the support ing base 0 of the raceway is unlocked, and the operator turns the said raceway around applying the balls to the bearing surfaces thereof until the row or series of balls extends wholly around the raceway when the treadle p is permitted to rise, first locking the raceway against rotary movement, and finally lowering the rotating platen until its ring/ rests upon the series of balls, and as it. rotates causes them to roll around the raceway so that they are presented to and pass by the grinding wheels again and again, presenting different points of their surfaces to the grinding wheels at differenttimes until all are ground down to uniform. size and true spherical shape. The grinding wheels 6 g aregradually fed inward as the grinding progresses, being moved on their carriages toward the raceway and balls supported thereon. The raceway b is made in a somewhat deep ring as shown in Fig. 3, and as its surfaces wear away and are reground or trued, the said ring gradually grows narrower and narrower, and it is necessary from time to time to adjust the platform 9 upon which the grinding wheels are supported vertically so as to bring the grinding wheels in proper position with relation to the supporting surface of the raceway. The rotating base or turn-table c on which the raceway is mounted may itself be supported on a series of balls as shown at 0 Fig. 1, so as to enable itto be turned easily by the operator in introducing the balls to the raceway and removing them therefrom.

The peripheries of the grinding wheels are concave in shape as shown in Fig. 2, the transverse curvature of their grinding faces corresponding to the curvature of the raceway so that substantially the whole width of the faces of the grinding wheels is effective for grinding the balls.

The entire support for holding the balls and carrying them past the grinding wheels, said support including the raceway ringb and the holding ring i constitutes a cylinder as shown in Fig. 3, in which the balls are held with their surfaces exposed at the periphery of the cylinder to'the grinding wheels which rotate about axes substantially at right angles with that of the supporting cylinder, and in the plane of the path of movement of the balls, and by having the raceway formed at one edge of the ring as shown, the ball supporting surface of the raceway may be renewed and kept trued by properly grinding the ring until substantially the whole of the ring is worn out.

I claim 1. The combination with the raceway and holding ring herein described, one having a rotary movement relative to the other of a grinding wheel to act in succession upon balls as they are carried across its face in the raceway.

2. The combination with the raceway herein described, of a relatively rotating holding ring to press the balls against the surfaces of the raceway and roll them around it, across the periphery of a grinding wheel.

3. A raceway for supporting aseries of balls while their surfaces are presented to themtion of a grinding wheel, such raceway having two supporting surfaces substantially at right angles with each other, one nearly horizontal but, toward the axis of the raceway, inclined downward, and the other nearly vertical but inclined upward toward the same axis, substantially as described.

4:. A support fora series of balls to be submitted to the action of grinding wheels, provided with a raceway for the support and movement of the balls, having surfaces substantially at right angles to one another, one to support the balls and the other to resist the thrust upon the balls of the grinding Wheels, and a ring having a surface to confine the balls and roll them along the raceway, substantially as described.

5. The combination of the raceway having capability of pivotal movement on its support and a rotating platen that engages with and rolls the balls on said raceway, and a grinding wheel operating on the balls opposite a portion of the raceway, with a look by which the raceway is engaged and withheld from rotation with different parts presented oppo' site the grinding wheel, substantially as and for the purpose described.

6. A machine for grinding balls having a cylindrical ring provided with ball supporting surfaces at the edge of one end thereof, and a platen having a ball engaging surface that confines the balls on said supporting surfaces and grinders for acting upon the said balls, substantially as described.

7. The combination of the raceway having a pivotal movement and provided with the ball supporting surfaces described with a platen having a ball engaging surface cooperating with balls on said supporting surfaces said platen being longitudinally movable with relation to the raceway for the purpose of enabling the balls to be introduced thereto and removed therefrom, substantially as described. I

8. The combination of the cylindrical support for the balls comprising a ring provided with a raceway at one edge thereof, and a bearing ring by which the balls areconfined on said raceway with a portion of their surfaces exposed outside of the cylindrical support; with grinding wheels that act upon the said exposed portions, and carriages for said grinding wheels movable toward and from the ball support, substantially as described.

9. The combination of the cylindrical support for the balls comprisinga ring provided with a raceway at one edge thereof, and a bearing ring by which the balls are confined on said raceway with a portion of their surfaces exposed outside of the cylindrical support; with grinding wheels that act upon the said exposed portions, and carriages for said grinding wheels movable toward and from the said ball support, and a support for said carriages adjustable in the direction of the axis of the cylindrical ball support, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JOHN J. GRANT.

\rVitnesses:

A. J. NIoHoLs, H. M. PUTNAM. 

